1. Field of the Invention
The present invention relates to a wire harness system.
2. Description of the Related Art
Recently, accompanying the outstanding development of electronics for vehicles, attempts have been made to form into modules various electronic units for mounting on vehicles, and to connect such individual modules together using a system that employs multiplex communication.
For example, disclosed in JP-A-10-22006 is a system wherein multiple actuators are arranged in a vehicle, and wherein, individually provided for each of these interface connectors, are multiplex communication control units that employ a LAN built into the vehicle.
According to this conventional technique, a protocol is established between the interface connectors by providing a CPU (Central Processing Unit) for each multiplex communication unit and by employing a communication method, such as a polling or a token passing method or the CSMA/CD method.
However, the conventional technique requires the establishment of a communication state among the multiplex communication units that are respectively provided for the interface connectors in a vehicle. Therefore, when the control data for multiple actuators are uniformly managed, the data transmission time is extended and practical control cannot be exercised. Accordingly, for the transmission or reception of data, it is extremely difficult to construct a large network that includes multiple actuators. And furthermore, when a communication problem occurs at a device installed in the vehicle and it is necessary to determine whether the problem is the result of a communication program malfunction or whether the problem originated at one, or at a combination, of the interconnected devices, since the system is one wherein communication is established by providing a CPU for each communication control unit, the source of the problem cannot easily be identified.
To resolve this shortcoming, a memory may be provided for each interface connector for the distribution of control data. However, in this case, either an extended processing time would be required to update the database of a host and the control data stored in the memories of the interface connectors, or a data transfer error could occur. Therefore, the number of actuators that could be connected to the individual interface connectors would be limited, and to construct a large communication system, the costs incurred for the required interface connectors would rise. Furthermore, since the time required to update data would also be increased, in consonance with the number of interface connectors, this configuration would not be appropriate for an actuator that must perform frequent transactions. Thus, it would be difficult to provide a practical large network, even when data used in common is provided for each interface connector.
To resolve the problems, it is one objective of the present invention to provide a wire harness system that can process data at a practical and an appropriate communication speed, even when control data is uniformly managed, and can thus enable the construction of a large network that includes multiple actuators.
To achieve this objective, according to the invention, a wire harness system comprises:
slave node connectors to be connected to multiple actuators;
a master node connector, including a controller for controlling the actuators connected to the slave node connectors; and
a multiplex communication system, for performing multiplex communication among the master node connector and the slave node connectors, including
a node address setting unit, for setting different node addresses for the node connectors,
token calling section, for one of the node connectors, provided for issuing a timing bit set as a token signal for each predetermined period of time, and
a token reception unit, for employing the timing bit set issued by the token calling section and the node addresses to provide a token for each of the node connectors in a time division manner.
According to the invention, when the controller provided for the master node connector performs multiplex communication with the slave node connectors in order to control the actuators, the token is provided for each node connector in a time division manner using the timing bit set that is issued as a token signal for each predetermined period of time and the node addresses set for the node connectors. Thus, a communication condition need not be established between the node connectors that exchange data, and the transmission/reception of data is enabled in a protocol-free state. Therefore, since among the node connectors the response time that is required for the exchange of data is drastically reduced, a large network incorporating multiple actuators can be constructed, and as for the actuators, control data that is be transmitted to the master node connector can be uniformly managed.
In addition, since a communication state is not established between the master node connector and the slave node connectors, a microprocessor need not be provided for the slave node connectors, thereby enabling the provision of a simple and inexpensive hardware configuration.
Further, since a complete time-division multiplex communication method is employed, the timing bit set output for each predetermined time and the node addresses need only be set so as to enable multiplex communication among the connectors. Therefore, the number of slave node addresses can be easily changed, and a change in the hardware specification for the wire harness can be easily coped with. As a result, when the wire harness of the invention is employed for a vehicle, a communication system that does not depend on the vehicle model can be constructed.
The slave node connectors and the actuators maybe connected by using a conventional wire harness, or the slave node connectors may be directly connected to the actuators.
Preferably, each of the node connectors includes a semiconductor relay for driving an actuator that is to be connected.
Since with this configuration the semiconductor relay for which maintenance is not required is distributed to each node connector, a conventional electric connection box need not be provided to correctly manage the drive relay, and the number of parts and cables can be reduced even more.
It is more preferable that the token calling section be provided for all of the node connectors, and that token adjustment section for adjusting the token signal based on the setting of the node addresses be provided for each of the token calling section, so that a data packet to be transmitted to one node connector can be received by another connector.
Since with this configuration, not only the master node connector but also all the other node connectors can serve as the master node, the system will not overall be halted when a fault occurs at the master node connector. That is, a degenerating operation can be performed by each of the node connectors that are connected to the multiplex communication path.
It is also preferable that the node connectors include a power feed switch connected to a power feed line along which power is supplied to the actuators.
In this case, the supply of power to the actuators can also be performed through multiplex communication.